DESIGN AND EXPERIMENTAL VERIFICATION OF A CLUTCHED PARALLEL ELASTIC ACTUATION MECHANISM FOR LEGGED LOCOMOTION

---

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, MAKİNE MÜHENDİSLİĞİ ANABİLİM DALI, Turkey

Approval Date: 2022

Thesis Language: English

Student: EMRE TANFENER

Principal Supervisor (For Co-Supervisor Theses): Ali Emre Turgut

Co-Supervisor: Uluç Saranli

Open Archive Collection: AVESIS Open Access Collection

Abstract:

This thesis presents modeling and system identification studies of a parallel elastically actuated robotic leg system and then details a clutch mechanism design to increase the overall efficiency of the system. The considered platform is a hopping mechanism constrained in the vertical axis that moves with the help of an electric motor and the integrated tension spring working parallel to the motor. To describe the dynamic motion of the mechanism, including the impact transitions, a linearized mass-spring-damper model and a non-linear model that considers inertial properties of the leg mechanism are considered. A data-driven approach is used to identify the physical parameters of these models. The experimental validation procedure shows the accuracy of the models to predict the motion of the system and implies the linearity of the passive dynamic structure of the mechanism. In addition to the modeling and identification studies, the joint mobility problem of the parallel elastic actuators is addressed. The proposed clutch mechanism intends to bring a compact and reliable solution to this problem while being compatible with the desired dynamic structure of the legged system. A preliminary test setup is used to assess some critical aspects of the clutch. Also, a modular and compact design is built and integrated on the existing parallel elastic hopper as a proof of concept.